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.\" Common Development and Distribution License ("CDDL"), version 1.0.
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.\" 1.0 of the CDDL.
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.\" Copyright 2015 Joyent, Inc.
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.Dd May 11, 2016
.Dt PCTFLD 3PROC
.Os
.Sh NAME
.Nm Pctlfd
.Nd obtain the process control file descriptor
.Sh LIBRARY
.Lb libproc
.Sh SYNOPSIS
.In libproc.h
.Ft int
.Fo Pctlfd
.Fa "struct ps_prochandle *P"
.Fc
.Sh DESCRIPTION
The
.Fn Pctlfd
function returns a file descriptor to the underlying /proc file system
.Sy ctl
file for the process identified by the handle
.Fa P .
This may be used for injecting control operations manually;
however, many interfaces for using it are provided by
.Xr libproc 3LIB
itself.
.Pp
Only live processes have a control file descriptor.
Process handles that correspond to files and cores, created through
.Xr Pgrab_file 3PROC
and
.Xr Pgrab_core 3PROC ,
do not have a corresponding file descriptor.
.Pp
The file descriptor is invalidated when the process handle is released
through
.Xr Prelease 3PROC
or if control is lost and the handle is reopened.
.Sh RETURN VALUES
Upon successful completion, the
.Fn Pctlfd
function returns a valid file descriptor.
Otherwise, if none exists, then
.Sy -1
is returned.
.Sh INTERFACE STABILITY
.Sy Uncommitted
.Sh MT-LEVEL
See
.Sy LOCKING
in
.Xr libproc 3LIB .
.Sh SEE ALSO
.Xr libproc 3LIB ,
.Xr Pcreate 3PROC ,
.Xr Pgrab 3PROC ,
.Xr Pgrab_core 3PROC ,
.Xr Pgrab_file 3PROC ,
.Xr Prelease 3PROC ,
.Xr Preopen 3PROC ,
.Xr proc 5
